You kind of have to do a workaround if you want to do that with PFlow (at least, I haven't been able to find an "object fragments" feature myself). To do it, you must create a group of "fragment" objects, which you will then tell PFlow to use as its particle type. When emitted, PFlow will then choose a random object out of the group you made for each particle, thus giving the illusion of lots of different fragments.
I wrote a tutorial on how to do exactly that on my website